Development of a new type of middle ear implant, a "middle ear balloon" is proposed. This implant is intended to restore hearing in non-aerated ears by creating and permanently maintaining an air or gas-filled space within the middle ear. Non-aerated middle ears resulting from eustachian tube dysfunction camonly occur in chronic otitis media (COM) and in otitis media with effusion (OME). The implant has significant potential as novel treatment for conductive hearing loss in patients with COM who have non-aerated ears, and in a subset of patients with OME when standard therapy has failed. A successful balloon implant must be easily fabricated, be biocompatible be easily compressible by sound vibrations, and must act as a physical barrier to fluid and gases. In Phase I, we successfully developed prototype balloon devices that meet these criteria. In Phase II, we propose to: 1) test long-term biocompatibility and safety using animal models; 2) assess long-term efficacy using laboratory-based testing; and 3) identify suitable technology for large scale manufacture. Completion of the proposed Phase II research should enable us to obtain an investigational device exemption from the FDA and to initiate prospective human clinical trials in follow-on, Phase III research. PROPOSED COMMERCIAL APPLICATION: The proposed balloon implant offers a novel method for treating conductive hearing loss due to non-aerated middle ears in chronic otitis media and some cases of otitis media with effusion. There is a large market potential for this implant, estimated at over 65,000 devices annually in the U.S. alone.